Sir Richard Dalton, a former British ambassador to Iran, has warned against attacking the country over its nuclear ambitions, saying doing so would “make the world a more dangerous place”.

He also said it would be illegal for the international community to launch military action against Iran without solid evidence that Tehran has developed nuclear weapons.

The former diplomat, now an associate fellow at international think-tank Chatham House, was speaking as a report by the United Nations nuclear watchdog expressed concerns that Iran may have other secret nuclear plants following the discovery of a facility hidden in a mountain near Qom.

Despite concerns that the site may only be capable of producing enriched uranium for weapons – rather than nuclear energy – Sir Richard urged continuing international dialogue to uncover the truth.